Exhaust gas system with two exhaust gas treatment units

Abstract

An exhaust gas system for an internal combustion engine includes a first exhaust treatment unit with a first back pressure and a second exhaust treatment unit with a second back pressure being higher than the first back pressure. The system advantageously enables the configuration of systems having two exhaust treatment units that are disposed one behind the other in flow direction. The first and/or second exhaust treatment unit can have a smaller construction due to the homogenization of flow. This applies, for example, when an oxidation-type catalytic converter is provided as the first exhaust treatment unit and when a particulate filter is provided as the second exhaust treatment unit. The homogenization of flow in the first exhaust treatment unit increases the conversion rate so that the first and/or second exhaust treatment unit can be provided with a smaller construction. This saves considerable costs when configuring such systems.

1. An exhaust gas system for an internal combustion engine, the exhaust gas system comprising:
 a first exhaust gas treatment unit with a first back pressure; and 
 a second exhaust gas treatment unit with a second back pressure being higher than said first back pressure; 
 said first exhaust gas treatment unit being disposed at a first distance upstream of said second exhaust gas treatment unit, in exhaust gas flow direction, causing a gas flow entering said first exhaust gas treatment unit during operation to be homogenized, said first distance being configured for causing an effect of said first back pressure and of said second back pressure to accumulate, and said first distance between said first exhaust gas treatment unit and said second exhaust gas treatment unit being less than 15 mm. 
 
     
     
       2. The exhaust gas system according to  claim 1 , wherein said first exhaust gas treatment unit has a gas inlet end side, and said second exhaust gas treatment unit has a gas inlet end side spaced from said gas inlet end side of said first exhaust gas treatment unit by a second distance of less than 60 mm. 
     
     
       3. The exhaust gas system according to  claim 1 , wherein said first exhaust gas treatment unit has a gas inlet end side, and said second exhaust gas treatment unit has a gas inlet end side spaced from said gas inlet end side of said first exhaust gas treatment unit by a second distance of less than 45 mm. 
     
     
       4. The exhaust gas system according to  claim 1 , wherein said first exhaust gas treatment unit has a gas inlet end side, and said second exhaust gas treatment unit has a gas inlet end side spaced from said gas inlet end side of said first exhaust gas treatment unit by a second distance of less than 30 mm. 
     
     
       5. The exhaust gas system according to  claim 1 , wherein said first exhaust gas treatment unit has an extent, in said exhaust gas flow direction, of less than 45 mm. 
     
     
       6. The exhaust gas system according to  claim 1 , wherein said first exhaust gas treatment unit has an extent, in said exhaust gas flow direction, of less than 35 mm. 
     
     
       7. The exhaust gas system according to  claim 1 , wherein said first exhaust gas treatment unit has an extent, in said exhaust gas flow direction, of 25 mm or less. 
     
     
       8. The exhaust gas system according to  claim 1 , wherein said first distance between said first exhaust gas treatment unit and said second exhaust gas treatment unit is less than 10 mm. 
     
     
       9. The exhaust gas system according to  claim 1 , wherein said first distance between said first exhaust gas treatment unit and said second exhaust gas treatment unit is less than 5 mm. 
     
     
       10. The exhaust gas system according to  claim 1 , wherein at least one of said exhaust gas treatment units includes at least one honeycomb body. 
     
     
       11. The exhaust gas system according to  claim 1 , wherein at least said first exhaust gas treatment unit includes a catalytically active coating. 
     
     
       12. The exhaust gas system according to  claim 1 , wherein said first back pressure and said second back pressure are in a ratio greater than 2. 
     
     
       13. The exhaust gas system according to  claim 1 , wherein said first back pressure and said second back pressure are in a ratio greater than 10. 
     
     
       14. The exhaust gas system according to  claim 1 , wherein said second exhaust gas treatment unit includes at least one component selected from the group consisting of:
 (a) an open particle filter; 
 (b) a closed particle filter; and 
 (c) an SCR catalytic converter.